1. Field of the Invention
The present invention relates to an optical member for use in ultraviolet region (for example, an optical member for use in a transmitting optical system such as laminated lens or prism) and a method of producing the same and, particularly, to an optical member suitable for use in the ultraviolet region of a semiconductor inspection device or the like and a method of producing the same.
2. Description of the Related Art
In conventional semiconductor inspection devices and other accurate measuring devices, inspection of a wafer or the like has been performed in an ultraviolet wavelength area of 200-400 nm, and a quartz (SiO2)-made lens or a fluorite (CaF2)-made lens is used in such semiconductor inspection devices for correction of chromatic aberration (achromatization).
For example, as shown in Japanese Patent Application Laid-Open No. 60-186444, it is known to protect the boundary part of the adhesive surface of a prism type optically adhered beam splitter for interferometer with the outside with a sealant.
An optical element having an adhesive member constituted as a film having both a film thermal adhesive layer and a barrier layer by using a thermally fusible film with high steam barrier property such as fluorine-based film is known as shown in Japanese Patent Application Laid-Open No. 2-287419, wherein CTFE (polychlorotrifluoroethane), FEP (polyperfluoroethylene-propylene), PVDF (polyvinylidene fluoride), PVDC (polyvinylidene chloride) and the like are used as the material of the film.
Further, as shown in Japanese Patent Application Laid-Open No. 60-176017, an optical element in which a rubber elastic body such as ethylene propylene rubber or silicone rubber which is transparent under visible light is put between two lenses which are not closely fitted, and the rubber elastic body is covered with a piezoelectric film such as polyvinylidene fluoride or the like is known.
In Japanese Patent Application Laid-Open No. 5-2105, as the material of an annular film constituting the film material, for example, thermoplastic resins and thermosetting resins such as polyethylene, polypropylene, polyvinyl chloride, polyamide, polystyrene, polyisobutylene, polycarbonate, polyvinilydene chloride, polyvinyl acetal, polymethyl methacrylate, polyacrylonitrile, polyimide, cellulose-based fluorine resin, epoxy, polyurethane, silicone resin; copolymers thereof; and those with plasticizer or filler added thereto are used.
As shown in Japanese Patent Laid-Open No. 2003-12349, a joined optical element for UV region is also known, which is formed through an adhesive layer by joining optical elements capable of transmitting ultraviolet rays, using as the adhesive layer a solution in which a solvent-soluble organic fluorine resin having no unsaturated bond in the molecule is dissolved in a fluorine-containing solvent having a boiling point of 150° C. or higher and containing no unsaturated bond in the molecule, vaporizing the solvent in the part in contact with atmosphere of the adhesive layer, and joining the optical elements in the state where the solvent in the other part is left in the adhesive layer.
The adhesion by use of a conventional sealant had problems as that the inside solvent is not hardened because it is not vaporized due to large adhesion distortion, a heating treatment cannot be performed because it affects a high precision lens, and an axial slippage is caused. Therefore, an extremely precise device such as semiconductor inspection device could not be suitably used in ultraviolet region.